1. Field of the Invention
The invention relates to an image forming apparatus which is connected to a network via network connecting means and can execute a predetermined job process and to a power control method.
2. Related Background Art
Hitherto, a system constructed by connecting printers (including a copying apparatus and a hybrid apparatus) and computers via a network exists.
FIG. 16 is a block diagram showing an example of a conventional network system including an image forming apparatus and corresponds to, for example, a construction of a network system which is used by a plurality of users in a network environment.
In FIG. 16, the network system is constructed by connecting a plurality of PCs (personal computers) 103a and 103b, a plurality of copying apparatuses 101a and 101b, and a server 102 via a network. The copying apparatus (each of the copying apparatuses 101a and 101b) is constructed by a printer unit 231, a reader unit 226, a controller unit 232, and a DC power source 203. The controller unit 232 transmits and receives signals to/from the outside, makes on/off control of the DC power source 203, and controls the reader unit 226 and the printer unit 231 via the network.
Ordinarily, when the copying operation and the printing operation are not executed for a predetermined time, the copying apparatus enters a sleep mode (power saving mode) in order to save energy.
Application software to manage the network has been known. By installing such software into the PC, a status of the copying apparatus connected to the network can be recognized. For example, if absence of sheets occurs, such a status of the copying apparatus can be displayed on a display screen of the PC. Even if the copying apparatuses 101a and 101b are in the sleep mode, when there is a print request from the PC connected to the network, it is detected, the DC power source 203 of the copying apparatus is activated, and the whole copying apparatus is activated, thereby performing a print output.
The foregoing conventional technique, however, has the following problems.
If an inquiry about the latest status of the image forming apparatus, for example, the copying apparatus connected to the network which is always updated is made by the PC when the copying apparatus is in the sleep mode, the controller unit 232 in the copying apparatus activates the DC power source 203, supplies a power source to all devices including various sensors in an engine, and detects the inquired status. To detect the status, the controller unit 232 communicates with the reader unit 226 and printer unit 231 and returns communication results to the network.
Therefore, in spite of the fact that the apparatus is in a state of the sleep mode in which the energy saving is accomplished, each time the status of the copying apparatus is inquired, it is necessary to supply the power source to the whole copying apparatus, or the power source of the copying apparatus always has to be kept in a current supplying mode. Such a situation is contradictory to a recent energy saving purpose.
A method whereby a current is supplied only to the sensors in the engine in the printer in the power saving mode only in the case where there is a status request from the application software for managing the network can be considered. However, it is presumed that under conditions such that a plurality of users share the printer, the status requests are frequently made by the plurality of users, so that a power saving effect cannot be expected.